This invention is directed to domestic appliances, such as convertible dishwashers, of the type which may be left in a free standing position, unattached to any structural components. Such convertible dishwashers are generally self supporting and rely entirely on the span between their support legs or casters to provide sufficient stability to balance the center of gravity of the dishwasher on its support members. The stability of these convertible dishwashers is dependent upon the overall size of the dishwasher unit and becomes a compromise of the large size needed for stability and the compactness needed to provide for the ease of location and storage of a convertible dishwasher.
Stability of convertible dishwashers is further affected by the off balance weight created when the door of a front loading dishwasher is opened and weight is applied to the door in its horizontal position. Such weight can be supplied by the withdrawal of the loaded lower dish rack to a position of full extension on the open door, or by the placement of the weight of the operator, or a child, on the open door by accident. Weight applied to the open dishwasher door operates against the weight of the dishwasher unit itself with the mechanical advantage of the leverage provided by the dishwasher door in its horizontal position.
In order to meet minimum standards of stability set by the Underwriters Laboratory, convertible dishwashers must remain in a stable, upright position under the stress of a 50-pound weight applied downwardly on the end of the opened door.
Attempts have been made to provide stability to convertible dishwashers by the utilization of heavier components in the dishwashers than are acceptable. Such weight increases provide additional stability at the expense of the ease of movement of the overall dishwasher unit. Increased cost of transportation of the units is also experienced by such a solution to the stability problem.
Other convertible dishwashers have been designed with the center of gravity shifted to the rear by movement of the front support members to a position in front of the pivot point of the dishwasher, which is the point where, conventionally, the front supports are located. The disadvantages of moving the front support members forward are that the support members are then exposed to view and the standard low cost support member is generally unattractive to the consumer. The alternatives are to use more expensive, attractive support members or to provide a shroud or nose piece which extends out past the extended support members and beyond the front plane of the closed dishwasher unit. The latter alternative is expensive, requires an additional manufacturing step and provides a dishwasher which has additional bulk and storage requirements.
Yet another method of providing stability to front loading convertible dishwashers is to provide articulating support members in addition to the main front supports. These members project outwardly and downwardly from the dishwasher upon movement of the dishwasher door from its closed vertical position to its open horizontal position. This method of providing stability to the open dishwasher incurs a large manufacturing expense and suffers from high service requirements. It also provides an apparent lack of quality due to the noise and moving components required to provide such articulating support members, as well as the requirement to provide accurate movement of the articulating support in a compound movement through a horizontal and vertical plane.
The patented prior art has recognized the problem of instability in dishwashers and the attendant problem of providing an attractive exterior to the functional designs created to increase dishwasher stability. This art is discussed below.
In U.S. Pat. No. 3,905,663, assigned to The Maytag Company, Bergeson discloses a convertible dishwasher which is designed to overcome stability problems by providing alternative mounting positions for the drive motor depending on whether the dishwasher is used as a free standing unit, wherein the motor is mounted at the rear of the unit to counterbalance the door, or as an installed unit, wherein the drive motor is mounted at the front of the unit so as to provide service access to same. In addition, this patent positions the front casters beyond the plane of the dishwasher front panel so as to create a greater floor space and, therefore, increase the unit's stability. A caster cover is provided over the exposed and porjecting front casters to at least partially cover said casters. Such a construction requires a permanent projection of the caster cover into the floor space immediately adjacent the front of the dishwasher unit.
In U.S. Pat. No. 3,912,350 assigned to Whirlpool Corp., Gurubatham describes an anti-tip mechanism for a free standing cabinet, such as a dishwasher. The mechanism includes a movable vertical panel which is maintained in a coplanar position with the front of the unit when the cabinet door is closed and is placed in a forwardly articulated position upon opening of the door. The vertical panel of the anti-tip mechanism has depending support legs which contact the floor when the panel for the anti-tip mechanism is in the forwardly extended position. Such an articulating mechanism requires considerable additional expense in manufacturing and results in a noisier, vibrational operation.
U.S. Pat. No. 3,393,950, assigned to Whirlpool, discloses a similar articulating support panel which is directly pivoted to the access door of an appliance cabinet so as to move through a horizontal and vertical path to provide support for the opened access door.
The art also recognizes other applications of the movable and pivotal panel in a cabinet structure such as U.S. Pat. No. 127,778; U.S. Pat. No. 1,080,074; and U.S. Pat. No. 3,645,594.
These attempts to overcome the stability problem of convertible dishwashers have a number of disadvantages as outlined above; namely, increased weight and costs, unattractive appearance, and lack of apparent quality due to mechanical movement of the stabilizers in compound movements.